Hi @Anandha L Ranganathan All the steps are covered in the ambari wizard for the downgrade, but you'll need to pay close attention to the various databases etc that require backing up as you go through. Both roll-back and full downgrade are possible.
Make sure you have satisfied all of the prerequisites before beginning as well, and preferably have read through the upgrade document several times to ensure you have accounted for everything.
http://docs.hortonworks.com/HDPDocuments/Ambari-2.2.2.0/bk_upgrading_Ambari/content/_upgrading_HDP_p...
I've performed a number of upgrades myself and while there is always the odd thing that crops up, its usually something minor that is easily fixed.
Good luck and I hope everything goes smoothly.